Synergistic effect of photocatalysis and adsorption of nano-TiO2 self-assembled onto sulfanyl/activated carbon composite.

We report a significant synergistic effect of photocatalysis and adsorption by depositing 3-6 nm TiO2 particles onto sulfanyl (HS)/activated carbon composite using molecular self-assemble method in low-temperature aqueous system. The synergistic effect was studied by comparing pure TiO2 and TiO2/sulfanyl/activated carbon composite to photocatalytic degrade methylene blue (MB) in a quartz glass reactor. The results showed that the photocatalytic activity of the TiO2/HS/AC composite compared to pure TiO2 has been greatly enhanced calculated from a simulated first-order kinetics model. The synergistic enhancement at low MB concentration was significantly stronger than that at high concentration, and the synergistic effect calculated from the model at initial concentration of 1 mg/L was approximately 64 times than at initial concentration of 15 mg/L. This is because when the adsorption rate was much faster than the photocatalytic degradation rate, strong adsorption of MB molecules may inhibit subsequent photocatalytic degradation reaction. The enhancement was found mainly due to the strong synergistic effect of the adsorption of MB of sulfanyl/activated carbon substrate and the photocatalysis of TiO2 nanoparticles.